Grindelia
pulchella
callus and cell suspension cultures were established from seedling
leaves. When several phytoregulator supplementations were assayed
in solid Murashige and Skoog medium containing 3% (w/v) of sucrose
(MS medium), combinations of indole-3-butyric acid (IBA) and N6-benzylaminopurine
(BA) resulted the most appropriate conditions to generate fast growing
friable calli with detectable levels of grindelic acid. Moreover,
the same basal media supplemented with 20.0 µM IBA/4.4 µM BA was found
to be optimal for cell growth in submerged cultures (µmax =
0.26 days-1) while the addition of 20.0 µM IBA/18.0 µM
BA resulted in a relative higher metabolite production (4.55 mg/gDW)
when the inocula was 5% (v/v). Furthermore, three different stress
factors and combinations of them were used to elicit cell suspensions.
These experiments demonstrated that the combination of CuSO4
and dimethylsulfoxide (DMSO) increase the grindelic acid production
to 2.63 mg/gDW in the elicited essay versus 0.756 mg/gDW in the control, at expense of cell growth.
In contrast, the addition of jasmonic acid (JA) alone and combined
with DMSO neither affected cell growth nor grindelic acid accumulation.